The present invention generally relates to an anti-electrostatic discharge spray gun apparatus and method for preventing crystallization of particles formed as a result of electrostatic discharge from forming on a spray gun nozzle and on a pair of oppositely charged electrodes disposed on the gun.
An anti-electrostatic discharge or electrostatic discharge-dissipating spray air gun apparatus is well known in the art. Such an apparatus may be used in clean rooms for the manufacture of semiconductors. The apparatus normally includes a spray gun housing, a conduit for passing a fluid or gas therethrough, flow control means, a nozzle disposed between the electrodes, and a positively charged and a negatively charged electrode that cooperate to form an electric field and then discharge or deionize electrostatically charged particles that pass through the field. Typically, upon operation of the spray gun, a large volume of gas such as compressed air or an inert gas including but not limited to nitrogen and argon, flows through the conduit, and then through the nozzle disposed between the electrodes. Then the electrodes then discharge electrostatic ions present in the gas. However, over time, aerosol particles formed from the electrostatic discharge of the gas dispensed through the nozzle can cause a crystallized build-up of a material such as ammonium nitrate on the electrodes and the nozzle. This contamination of the electrodes and the nozzle can erode the electrodes and the nozzle, thus preventing the electrodes from performing their anti-electrostatic discharge function and preventing the nozzle from dispensing the gas.
The present invention provides a new deionizing or anti-electrostatic discharge air gun that avoids crystallization resulting from electrostatic discharge from forming on the electrodes and the nozzle.
It is therefore an object of the present invention to provide an apparatus for preventing particle build up on the electrodes in an anti-electrostatic discharge or electrostatic discharge-dissipating air gun that does not have the drawbacks or shortcomings of the conventional electrostatic air guns.
It is another object of the present invention to provide a method for preventing or reducing particle build up on the electrodes that utilizes a steady flow of compressed air or an inert gas such as nitrogen to prevent crystallization of the electrodes.
It is a further object of the present invention to provide an apparatus that will not erode electrodes or a nozzle of an anti-electrostatic spray gun.
In accordance with the present invention, an apparatus and method for preventing electrostatic discharge from contaminating a nozzle and an electrostatic discharge-dissipating device are provided.
In a preferred embodiment, an anti-electrostatic discharge spray gun apparatus for preventing electrostatic discharge from causing crystallization of the nozzle has:
(a) a housing;
(b) a nozzle attached to the housing having an orifice for dispensing gas;
(c) means for dispensing a gas through the nozzle;
(d) means for electrostatically discharging ions in a gas dispensed through the nozzle; and
(e) means for restricting the flow of a gas through the nozzle.
The anti-electrostatic discharge spray gun is further directed to a hose in communication with a gas flow source and in further communication with the nozzle; a handle movably attached to the housing, wherein the handle is capable of moving between a first position and a second position wherein the handle is normally biased in the first position; and a trigger valve in communication with the hose wherein the hose, handle and trigger valve cooperate to define the means for dispensing a gas through the nozzle.
Additionally, the present invention is further directed to a bypass piping that operates to provide a constant but low volume flow of gas through the nozzle. The bypass piping further defines the means for restricting the flow of a gas through the nozzle.
In an alternative embodiment, the present invention is directed to a stopper that defines the means for dispensing gas through the nozzle and the means for restricting the flow of a gas through the nozzle. The stopper is disposed between the handle and the trigger valve that is in communication with the hose and cooperates with the handle and the trigger valve to provide a steady but low volume flow of gas through the nozzle.
Preferably, the means for electrostatically discharging ions in a gas dispensed through the nozzle is a pair of charged electrodes, each having an opposite polarity that cooperate to form an electric field for discharging ions present in the gas dispensed through the nozzle.
Additionally, a method of using the anti-electrostatic discharge apparatus is disclosed herein. The method provides for a steady flow of an inert gas to flow through the nozzle to prevent contamination, resulting from electrostatic discharge, of the electrodes and the nozzle.